Slide drive mechanism for a press

ABSTRACT

A SLIDE DRIVE MECHANISM FOR A PRESS IN WHICH A SLIDE ACTUATING SHAFT IS PROVIDED WITH AN ECCENTRIC SHEAVE ADAPTED TO CAUSE A CONNECTING ROD CONNECTED TO THE SLIDE OF THE PRESS TO RECIPROCATE. THE SLIDE ACTUATING SHAFT HAS IMPARTED THERETO A NON-CONSTANT ANGULAR VELOCITY MOVEMENT FROM A DRIVE SHAFT WHICH ROTATES AT A CONSTANT ANGULAR VELOCITY AND IMPARTS A NON-CONSTANT ANGULAR VELOCITY ROTATIONAL MOVEMENT TO THE SLIDE VIA AN INTERMEDIATE TRANSMISSION MEANS.

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angle of main 96"" United States Patent O 3,572,137 SLIDE DRIVE MECHANISM FOR A PRESS Kohji Nakano, Kanagawa-ken, Japan, assignor to Kabushiki Kaisha Aida Tekkosho, Sagamihara-shi,

Kanagawa-ken, Japan Filed May 21, 1969, Ser. No. 826,475 Int. Cl. F16h 21/22 US. CI. 74-44 2 Claims ABSTRACT OF THE DISCLOSURE A slide drive mechanism for a press in which a slide actuating shaft is provided with an eccentric sheave adapted to cause a connecting rod connected to the slide of the press to reciprocate. The slide actuating shaft has imparted thereto a non-constant angular velocity movement from a drive shaft which rotates at a constant angular velocity and imparts a non-constant angular velocity rotational movement to the slide via an intermediate transmission means.

BACKGROUND OF THE INVENTION When the slide of a press is driven by a conventional slide drive mechanism, the stroke or displacement and velocity curves drawn by the slide as the slide moves toward and away from a workpiece to be processed are curves which are similar to a cosine curve and the descending stroke velocity of the slide is at a maximum value at a point adjacent to the midpoint of the stroke. In a general drawing press, when the drawing rate exceeds a predetermined value, a workpiece being processed will be adversely affected thereby and in an extreme situation, the workpiece cannot be processed to a desired product. Hence, the drawing rate by the conventional drawing press has been inevitably subjected to a limitation. Thus, when the length of the stroke of the slide is once determined, the frequency of the stroke for the processing operation of the slide per unit of time will be determined depending upon the determined length of the stroke. Under this circumstance, when it is desired to increase the frequency of the stroke for the processing operation of the slide, there is no alternative approach but to have the slide move toward and away from a workpiece in a non-cosine curve movement in which the slide moves downwardly at an accelerated velocity covering a distance from the upper dead point to a substantially mid-point of its descending stroke and it moves at the accelerated velocity in the upward stroke from the lower dead point to the upper dead point during which the slide executes no processing operation on the workpiece while maintaining the velocity in the processing stroke of the slide at a substantially constant value.

SUMMARY OF THE INVENTION The present invention relates to a slide drive mechanism for a press and more particularly to a slide drive mechanism for a press adapted to reduce the idle time during which the die on the slide and that on the bolster execute no processing operation on a workpiece for increasing the frequency of the stroke for the processing operation by the slide per unit of time.

One object of the present invention is to provide a slide drive mechanism in which a rotary shaft having an eccentric sheave adapted to cause a connecting rod connected to the press slide to move, has reciprocally imparted thereto, a non-constant angular velocity rotational movement from a main drive shaft rotatable at a con- "ice stant angular velociy rotational movement through an intermediate transmission means.

Another object of the present invention is to provide a slide especially for use in connection with a drawing press to drive the press slide whereby the slide is caused to move toward a workpiece to be processed at an accelerated velocity to allow the die on the slide and the die on the bolster to cooperate to perform a processing operation on the workpiece for a relatively increased period of time suflicient to execute a desired processing operation and after the completion of the operation, the slide is moved away from the workpiece at the accelerated velocity.

A further object of the present invention is to provide a slide drive mechanism for a press adapted to effect an increased frequency of stroke for processing by the slide per unit of time as compared with that obtainable by conventional slide drive mechanisms.

The above and other objects and attendant advantages of the present invention will be more readily apparent to those skilled in the art from the following description and accompanying drawings, and in which drawings:

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a front elevational view of a press in which one preferred form of slide drive mechanism according to the present invention is incorporated,

FIG. 2 is a fragmentary view partly in elevation and partly in cross-section on an enlarged scale showing the principal parts of the slide drive mechanism of FIG. 1,

FIG. 3 is a view taken substantially along the line IIIIII of FIG. 2, the view looking in the direction of the arrows,

FIG. 4 is a view taken substantially along the line IVIV of FIG. 2 the view looking in the direction of the arrows,

FIG. 5 is a diagram for comparing the slide displacement curve obtainable by the slide drive mechanism of the present invention with those obtainable by conventional link-type and crank-type slide drive mechanisms, respectively, and

FIG. 6 is a diagram for comparing the slide movement velocity curve obtainable by the slide drive mechanism of the present invention with those obtainable by conventional link-type and crank-type slide drive mechanisms, respectively.

DETAILED DESCRIPTION OF INVENTION The present invention will now be decsribed referring to the accompanying drawings and particularly to FIG. 1 thereof in which a press having one preferred form of slide drive mechanism incorporated therein is shown.

The press generally comprises a framework 1, a slide 20 movably mounted on the framework in a suitable conventional manner for vertical reciprocal movement and adapted to support a die (not shown) on the underside thereof and a bolster 21 on which a mating die (not shown) is adapted to be held in position. The slide 20 is adapted to have vertical reciprocal movement imparted thereto from a novel drive mechanism, to be later more fully described in connection with FIGS. 24, through a pair of plungers 22 arranged in a side-by-side spaced relationship. Since the actuating means for driving the plungers 22 are identical in construction and operation, for clarification of the illustration, only one plunger actuating means is illustrated in FIGS. 24. The press further comprises an electric motor 23 suitably mounted on the framework 1 for operating the press. When activated, the electric motor 23 drives, by means of a belt-type transmission means 24, a fly wheel 25 fixedly mounted at one end of a press drive shaft 27 which is journalled in bearings 33 suitably supported in the framework 1. The transmission means 24 is trained over the output shaft of the electric motor 23 and the fly wheel 25. When driven as above mentioned, the fly wheel 25 in turn drives the press drive shaft 27 by means of a conventional clutch 26.

A slide drive intermediate shaft 3 is journalled in bearings 34 suitably supported by the framework 1 and a gear 29 is fixedly secured to one end thereof. The gear 29 meshes with a mating gear 28 fixedly mounted on the shaft 27 at a point inwardly spaced from the fly wheel 25 whereby the slide drive intermediate shaft 3 has imparted thereto a constant angular velocity rotational movement from the drive shaft 27 through the gears 28 and 29. The other end of the intermediate shaft 3 has a gear 30 fixedly secured thereto which is in mesh with an annular main gear 2 rotatably supported on support members 31 and 31' fixedly carried by the framework 1. The annular main gear 2 is provided with an eccentric pin 4 to which one end of a link 5 is pivoted. The other end of the link 5 is pivoted to a lever 7 by a pin 6 and the lever 7 is fixedly mounted on one end of a slide actuating shaft 8 journalled on bearings 32 suitably supported by the framework 1.

The shaft 8 also is provided with an eccentric sheave 9 integrally secured thereto at an intermediate point between the opposite ends of the shaft and a bifurcated lever 17 is rotatably mounted on the eccentric sheave 9. The one end or arm of the lever 17 pivotally supports one end of a connecting rod by a pin 14. The other end of the connecting rod 15 is pivoted by a pin 16 to the plungers 22 which, in turn, are suitably connected to the slide in a conventional manner. The other end or arm of the lever 17 pivotally supports one end of a link 11 while the other end of the link is pivoted by a pin 12 to a support member 13 fixedly mounted on the framework 1.

In the slide drive mechanism, since the intermediate shaft 3, eccentric pin 4, link 5, pin 6, lever 7 and shaft 8 cooperate with one another to constitute a so-called double crank mechanism, when the intermediate shaft 3 has imparted thereto a constant angular velocity rotational movement by the gear 29, a non-constant angular velocity rotational movement is imparted to the actuating shaft 8. Since one arm of the lever 17 is connected through the pin 10, link 11 and pin 12 to the support member 13 and the other arm is connected through the pin 14, connecting rod 15 and pin 16 to the slide 20 (distinguished from the conventional arrangement in which the sheave rotates at a constant angular velocity rotational movement), the slide on which the die is mounted is caused to move rapidly toward a workpiece to be processed (descending stroke) and away from the workpiece after the completion of a desired process (ascending stroke) respectively, thereby obtaining the displacement curve A and the stroke velocity curve B as shown in FIGS. 5 and 6, respectively. This is due to the fact that the sheave 9 rotates at a non-constant angular velocity.

As mentioned above, according to the invention, the fact that the eccentric sheave 9 which transmits the rotational movement of the intermediate shaft 3 through the double crank mechanism to the slide has imparted thereto a non-constant angular velocity rotational movement, the idle time during a cycle of operation of the press may be reduced and the slide may move toward and away from the workpiece at a high velocity thereby increasing the frequency of stroke by the slide for a processing operation per minute. Furthermore, the present slide drive mechanism extends the service life of the dies employed in the press.

FIG. 5 illustrates a diagram in which the displacement curve to be drawn by the slide when the slide is driven for a given cycle of time by the present slide drive mechanism and that drawn by the same slide when the slide is driven for the same cycle of time by conventional linktype and crank-type drive mechanisms, respectively, for comparison purposes. In FIG. 5, A designates the displacement curve drawn by the slide when the slide is driven by the present slide drive mechanism and a and a the displacement curves when the slide is driven by the conventional link-type and crank-type slide drive mechanisms, respectively.

FIG. 6 discloses a diagram in which the velocity curve to be drawn by the slide when the slide is driven for a given cycle time by the instant slide drive mechanism and that to be drawn by the same slide when the slide is driven for the same cycle time by conventional link-type and crank-type slide drive mechanisms, respectively, for comparison purposes. In FIG. 6, B designates the velocity curve drawn by the slide when the slide is driven by the present slide drive mechanism and b and b the velocity curves when the slide is driven by conventional slide drive mechanisms, respectively. As can be seen from these figures, according to the present invention, the length of the idle time in one time cycle of operation is less than those for the same time cycle when the same slide is driven by the conventional slide drive mechanisms.

One most important difficulty which has been experienced in designing presses or press lines which are assigned to perform successive step processes on a workpiece and in which the slide in each press moves drawing a cosine curve in its stroke movement is that the frequency of the processing operation is limited by the press or presses at the drawing step of the entire operation to a value less than that for which the presses have been designed. However, according to the present invention, such a difficulty can be effectively eliminated.

Referring again to FIGS. 5 and 6, it is assumed that the cycle time is the same for all situations and that the drawing velocity in each situation is measured with the drawing operation starting point set at D and, as a consequence, the drawing velocity ratio for Bzbzb will be 1:l.95:3.26. Therefore, if the drawing velocity is the same for all situations, for example, the drawing velocity is set as max. 23 m./min., then the present slide drive mechanism can provide a drawing velocity of 1/3.26 of that for a conventional crank-type slide drive mechanism. This slow drawing is also advantageous with respect to the service life of the dies employed in a press. When the conventional crank-type slide drive mechanism allows the press slide to execute 20 strokes per minute for the processing operation, the present slide drive mechanism allows the press slide to execute as many as about 65 strokes per minute for the processing operation during the same time period.

While one preferred embodiment of the invention has been shown and described in detail, it will be understood that the same is for the purpose of illustration only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. A slide drive mechanism for a press including a frame, a slide mounted on the frame for reciprocal movement, a press drive shaft, a slide drive intermediate shaft, complemental gear means on said shafts whereby a constant angular velocity rotational movement is imparted to the intermediate shaft from the drive shaft, an annular gear rotatably supported by the frame, gear means on the intermediate shaft in mesh with the annular gear, a connecting rod connected to the slide for imparting reciprocal movement thereto, a slide actuating shaft, an eccentric sheave on said actuating shaft operably connected to said connecting rod, and a double crank connection between the annular gear and said actuating shaft for imparting a non-constant angular velocity rotational movement to the actuating shaft whereby the slide is caused to move rapidly toward a workpiece to be processed and away from the workpiece after completion of the processing, respectively.

2. The slide drive mechanism for a press as claimed in claim 1, in which said double crank mechanism includes a pin eccentrically mounted on said annular gear, a lever fixedly mounted on said slide actuating shaft, and a link operably connecting said eccentrically mounted pin and lever, a bifurcated lever loosely mounted on said sheave, means pivotally supporting one end of the connecting rod on one arm of said bifurcated lever, and means pivotally supporting the other arm of said bifurcated lever an the frame of the press.

References Cited UNITED STATES PATENTS 1,876,129 9/1932 Arnold 74-571 2,550,063 4/1951 Johansen 7444 5 2,834,223 5/1958 Strand 74571 2,962,993 12/1960 .Tohansen 7444 FRED C. MATT-ERN, JR., Primary Examiner 10 W. S. RATLIFF, JR., Assistant Examiner 

